Processes of this kind are employed on a large scale in the recovery of metals from ores. After the metals are brought into an aqueous solution, the required metal ions are then extracted from such solution. In addition, this process is also employed for the recovery of metals from waste streams originating, for instance, from the electroplating industry, catalyst processing and the like.
Various materials have been used as organic extracting agents, such as thiobenzoylmethane dissolved in benzene or chloroform, together with a pyridine derivative, for extraction of nickel (See J. Inorg. Nucl. Chem. 31 (1969) p. 2612). For extraction of copper, nickel and cobalt, pyrophthalone or 5-nitropyrophthalone may be used (Russion Journal of Inorganic Chemistry, 18 (1973) no. 8). In addition, a great number of other extracting agents are known which are based on .alpha.- or .beta.-hydroxyoxime compounds. One characteristic of these various extracting agents is that their use is, in most cases, expensive while a number of them exhibit undesirable, toxic properties. A general review of metal-extraction is given in Chemical Engineering, Aug. 30, 1976, pp. 86-94.
The purpose of the present invention is to provide a less expensive extracting agent which is simple to employ and which is also relatively non-toxic.
This invention has been developed by work of the above named inventors with the technical assistance of the Technical University at Eindhoven.